E2BADMA (dimethacrylate of bisphenol A alkoxylated with 2 ethylene oxide units in each case) and E3BADMA (dimethacrylate of bisphenol A alkoxylated with 3 ethylene oxide units in each case) are bisphenol A-based dimethacrylates which are used as crosslinkers, for example in coatings and mixtures for drillholes. They are notable for a rapid reaction time which leads to partial load-bearing capacity of 2-pack mixtures even after a short time and attainment of the final tensile strength after a few hours. In addition, they have a high polymer density with a very good cohesion/adhesion ratio, good crystallization resistance with simultaneously low shrinkage and a low tendency to embrittlement, and high wetting power in order to assure good creeping capacity in capillary cracks.
DE 41 31 458 A1 discloses two-pack adhesive compositions for chemical securing technology, comprising a synthetic resin comprising the di(meth)acrylate of an alkoxylated bisphenol and a hardener for the synthetic resin.
For particular applications, bisphenol A-free crosslinkers having a similar profile of properties are being sought.
Isosorbide is a diol based on renewable raw materials and, in structural terms, is an alternative to bisphenol A, since it has a similarly rigid base structure.
One means of preparing di(meth)acrylates from isosorbide is the esterification of isosorbide with (meth)acrylic acid or the transesterification of methyl acrylate, ethyl acrylate or methyl methacrylate with isosorbide in the presence of suitable catalysts. Both OH groups of isosorbide are secondary OH groups having comparatively low reactivity, and the relative reactivities of the two OH groups are additionally very different. Thus, incomplete conversion is to be expected.
DE 2 317 226 A1 discloses a method of preparing (meth)acrylic esters from a mixture of C10-C18 alkanols by transesterification of methyl (meth)acrylate in the presence of titanium alkoxide as catalyst and 2,6-di-tert-butylparacresol (TBC) as stabilizer. This method is carried out in the presence of activated carbon. Once the reaction has ended, water is added to hydrolyze the titanium alkoxide to titanium hydroxide/oxide which adsorbs onto the activated carbon. The solid is filtered off and the reaction product is subjected to a steam distillation.
WO 2009/080380 discloses a process for preparing methacrylates of C6-C22 alcohols by transesterifying methyl (meth)acrylate with the appropriate alcohols in the presence of titanium alkoxide as catalyst. In example 1, methyl methacrylate is reacted with 2-ethylhexanol in the presence of hydroquinone monomethyl ether (MEHQ) as stabilizer and tetraisopropyl titanate as catalyst. An azeotropic mixture of methanol/methyl methacrylate is distilled off. After distilling off unconverted methyl methacrylate, the catalyst-comprising 2-ethylhexyl methacrylate is subjected to a purifying distillation under reduced pressure (about 30 mbar). This affords 2-ethylhexyl methacrylate in 99.4% purity.